Met-Rx vs. Slim Fast

May 15, 2009 1:39 AM

Meal Replacement Shakes for weight loss - can I mix and match?

I am currently wanting to lose about 10kg before my summer holidays start. I am going on a 5k jog every other day and doing pushups. This post is not about exercise though. I also decided to use a meal replacement shake to help control my calorie intake.

I ordered 3 tubs (12 servings per tub) of Slim Fast powder at a cost of £15. These have 218 calories per serving. Full Nutritional Details [PDF]

I received these and started taking one for breakfast, one for lunch, and then having a 600 calorie evening meal, as suggested by Slim Fast. I then did some more reading, and an article I found suggested that after I had stopped taking the Slim Fast, and gone back to solids, I would gain the weight back very fast.

So I ordered 20 servings of Met-Rx Meal Replacement Shakes at a cost of £20. These have about 250 calories per serving.
more details here.

So, my question comes in two parts:

1. If I just use Slim Fast, which I'd like to do as it's cheaper (even if not as filling as Met-Rx) will I gain the weight back fast after I stop taking the Slim Fast?

2. If so, might it be possible to have a Slim Fast for breakfast, and a Met-Rx for lunch, without any negative effects?

posted by edbyford to health & fitness (11 comments total)

1. If you don't continue to control your calorie intake (well in/out balance), yes you will. But that's not limited to the slim fast, it will be the same with the Met-rx or just a plain ol' calorie restricted diet. Ultimately if you don't change your eating habits you will regain the lost weight (and possibly more)

2. IANAD but I don't see why not, they're both just meal replacement shakes. They work by restricting calorie intake in a 'healthy way' (ie. they pack them full of more vitamins and minerals than you could get from the same calorie value of real food).
posted by missmagenta at 2:48 AM on May 15

1. Yes. I've always believed that the whole point of the shakes was not so much to help you lose weight (although they do) but to change your eating habits to such a degree that when you stop, you'll hopefully keep the weight off.

2. IANAD, but yeah, should work a treat.
posted by Effigy2000 at 3:19 AM on May 15

I wish I could find the link to the article, but I seem to remember the article saying that it was something to do with the composition of the Slim Fast (amount of sugar?) which would cause you to lose lean muscle, and therefore put the weight back on again. Can someone confirm/deny that?
posted by edbyford at 3:35 AM on May 15

You will shed some lean muscle on pretty much any diet that is very calorie restrictive. The met-rx claims it helps build lean muscle but its really designed as a post-workout shake for body builders rather than a meal replacement shake (there's no reason it can't be used as that but don't expect to be building muscle while you're on a huge calorie deficit)
posted by missmagenta at 4:01 AM on May 15

So do you think the best thing for me to do would be to use the Slim Fast to lose weight, then when I'm at my target weight start using the Met-Rx to build muscle instead of gain fat?
posted by edbyford at 5:13 AM on May 15

Why are you using these shakes rather than something like a tub of protein powder? The idea is the same, you just have to mix it yourself? If traveling is a problem, you can buy a shaker bottle.

It's much, much cheaper. It'll also have more protein that the Slim Fast drink (the Met-Rx drink should have a ton) which will, in an ideal situation, help maintain your lean body mass. You don't just want to lose weight, you want to lose fat.
posted by Loto at 5:57 AM on May 15

I don't see why you can't mix them. I *do* see in my 2 minute, non-nutritionist review that the Met-Rx looks more like what I would want - more protein, no added sugars and lower carbs (Slim Fast has almost 30g of sugar alone), no aspartame.

You will lose some lean muscle on any diet - if there were a diet that allowed you to lose pure fat we would be hearing about it non-stop, I am pretty sure. You're not going to gain muscle just by drinking the Met-Rx, although the protein helps if you are doing the strength building workouts, so I don't know why you couldn't use it during both phases you mention, but I'll leave that to someone with more bodybuilding smarts than me.

When you stop the meal replacements, either of them, it will be a challenge not to gain weight, because you have to figure out what to eat instead of being able to grab a shake. The temptation (freedom) of choosing what to eat all day long is in a lot of cases harder than knowing you can have 2 shakes and a 600 calorie dinner.
posted by KAS at 6:03 AM on May 15 [1 favorite]

The best thing for me to do would be to use the Slim Fast to lose weight, then when I'm at my target weight start lifting weights to build muscle.

FTFY.

The 'losing muscle' thing - don't worry about it until you start looking like the guy from the machinist. It's something bodybuilders worry about when getting under 5% bodyfat without losing their definition and it somehow got mixed up with workout advice for normal people.

also keep in mind protein shakes aren't special elixirs, just concentrated food. Mix and match whatever you like as long as your stomach can take it.
posted by anti social order at 7:02 AM on May 15

Not all meal replacement shakes are created equal. I personally wouldn't touch Slim-Fast (to much garbage in it) or Met-Rx (to expensive...last time I checked).

Personally, I prefer Biotest (Metabolic Drive or Grow). They have always backed up their claims, and even offer a money back garauntee. Although it looks like the protein shakes are excluded.
posted by P.o.B. at 4:04 PM on May 15

Good point. Met-Rx is expensive. I looked at the link you sent me, P.o.B. Correct me if wrong, but they're all protein shakes. Isn't the trouble with drinking a shake which is just for protein going to mean that I end up getting bigger? I chose 'meal replacement' shakes because I hoped they are going to do just that - provide normal levels of vitamins, carbohydrates etc which I would get from a meal with fewer calories.

With that in mind, any more recommendations?
posted by edbyford at 12:02 AM on May 16

Isn't the trouble with drinking a shake which is just for protein going to mean that I end up getting bigger?

Well, quite simply, no. If you are not overindulging in extra calories, you won't get "bigger". This would hold true as long as you are keeping tabs on your metabolic input/output.
Personally, when I make my shakes I mix it with yogurt and fruit so I get the carbs I want anyway. It is a meal replacement for me.
posted by P.o.B. at 1:50 AM on May 16